Prior to Sup, Stein was the co-founder of another social app, Stamped. Stamped let people list their favourite things, and it was acquired by Yahoo in October 2012. But Rabois, who was COO of Jack Dorsey’s hot startup Square back then, also wanted to acquire Stamped. The local information Stamped was collecting from users was interesting to Square, which works with local vendors to accept mobile payments.

But Stein and his co-founders turned Rabois down in favour of Marissa Mayer, who had recently become CEO of Yahoo. “They were crazy enough to turn me down for Yahoo,” Rabois told Business Insider while discussing his investment in Sup this week.

Why did a startup choose a struggling media company over one of the hottest startups in the world? (keep in mind this was two years ago, before Square’s business struggles were made public.)

The Stamped founders previously worked at Google under Marissa Mayer, so they were familiar with her. “As a team of mostly former Googlers, we’ve all worked with and are big fans of Marissa,” Stein wrote on Stamped blog post when the startup was acquired.

Also, Mayer was willing to let the Stamped team stay in New York. Stamped was the first startup Mayer bought before she went on a buying spree, snatching up dozens of companies including $US1 billion Tumblr. She also promised to let Stein and his partners help build up Yahoo’s New York office.

If you ask Stein now why he chose Yahoo over Square, his answer is the same. “Square and Stamped were both in the local space, and Stamped had built a core technical competency in that area,” Stein told Business Insider via email. “We loved Keith and the team at Square but Marissa gave us an opportunity to build an office for Yahoo in New York City, which was too exciting an opportunity to pass up (and it let us stay in NYC!)”